Ceramic Discharge Vessel Having a Sealing Composition

a ceramic discharge and composition technology, applied in the manufacture of cold cathode, electric discharge tube/lamp, electrode system, etc., can solve the problems of restricting the types of lamp configurations, corroding iodide salts with respect to some lamp materials, etc., to achieve less expensive, wider range of sizes, complexity and/or functionality

Inactive Publication Date: 2008-08-28
OSRAM SYLVANIA INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0009]Thus, discharge vessels using the sealing composition of this invention may be formed in a wider range of sizes, complexity, and / or functionality compared to current state-of-the-art ceramic discharge vessels, e.g., more compact and / or longer-life lamps. In addition, the sealing composition should be less expensive than the rare-earth-containing Al2O3—SiO2—Dy2O3 frit.

Problems solved by technology

However, even the iodide salts are corrosive with respect to some lamp materials especially at high temperatures.
The elongated capillaries however impose size limitations on the discharge lamp which in turn restrict the types of lamp configurations which may be used.

Method used

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  • Ceramic Discharge Vessel Having a Sealing Composition
  • Ceramic Discharge Vessel Having a Sealing Composition
  • Ceramic Discharge Vessel Having a Sealing Composition

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example

[0015]A sealing composition corresponding to quasibinary eutectic A was made by combining, in percent by weight, yttrium oxide (59.9%), aluminum oxide (27.0%), and magnesium oxide (13.1%) powders. The oxide mixture was mixed by ball milling in a plastic jar with de-ionized water and high-purity alumina media. After mixing, the oxide mixture was dried and fired in air at 900° C. to partially sinter the oxide particles together so that the mixture would remain homogeneous during the remaining processing steps. The fired mixture was then mixed with a polyvinyl alcohol binder and pressed into small rings suitable for sealing ceramic metal halide lamps. The sealing rings were partially sintered in air at 1250° C. prior to sealing tests.

[0016]Sealing / joining tests were performed using three different types of heating equipment: a tungsten-coil furnace, RF heating, and laser heating. Crack-free seals were made on 70 W discharge vessels having multi-strand electrode feedthroughs. Tungsten c...

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Abstract

A sealing composition for ceramic discharge vessels is described. The sealing composition contains about 20 to about 40 mole percent MgO, about 20 to about 45 mole percent Y2O3, and about 20 to about 60 mole percent Al2O3 and has a melting point of less than about 1800° C., and preferably from about 1700° C. to about 1800° C. The sealing composition may be used for making ceramic-to-ceramic or ceramic-to-metal seals in ceramic discharge vessels.

Description

BACKGROUND OF THE INVENTION[0001]Metal halide and high-pressure sodium lamps are two examples of lamps which use a discharge vessel, also known as an arc tube, made of a ceramic material. The preferred ceramic material for these arc tubes has been polycrystalline alumina (PCA). The robustness of the ceramic material permits the use of more corrosive chemical fills and allows the discharge vessels to be operated at higher temperatures. A sealing composition, commonly referred to as a frit, is used to form a hermetic seal between the feedthrough sections of the electrodes and the ceramic body of the discharge vessel. The sealing composition may also be used to join together the ceramic pieces which form the discharge vessel. The sealing composition is designed to have a lower melting point than the ceramic components so that the seals may be formed without additional sintering / shrinkage of the ceramic vessel. The sealing composition must be resistant to attack by the chemical fill whi...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H01J61/36C09D1/00
CPCH01J61/302C04B35/44C04B35/443C04B37/005C04B2235/3217C04B2235/3225C04B2237/064C04B2237/343C04B2237/72H01J9/266H01J61/361H01J61/366
Inventor HECKER, ARLENE
Owner OSRAM SYLVANIA INC
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